With respect to the given diagram, which of the following correctly matches the information in Part $I$ and Part $II$ ?

Part $I$	Part $II$
$1.$ $\overline{ OA } \cup \overline{ OB } \cup \widehat{ APB }$	$a.$ Major sector
$2.$ $\overline{ AB } \cup \widehat{ AQB }$	$b.$ Minor segment
$3.$ $\overline{ AB } \cup \widehat{ APB }$	$c.$ Minor sector
$4.$ $\overline{ OA } \cup \overline{ OB } \cup \widehat{ AQB }$	$d.$ Major segment

Is the following statement true? Give reasons for your answer.

Area of a segment of a circle $=$ area of the corresponding sector - area of the corresponding triangle.

Find the radius of a circle whose circumference is equal to the sum of the circumferences of two circles of radii $15 \,cm$ and $18 \,cm$ (in $cm$)

The radit of two concentric circles are $23\, cm$ and $16 \,cm .$ Find the area of the circular ring formed by the circles. (in $cm^2$)

An archery target has three regions formed by three concentric circles as shown in $Fig.$ If the diameters of the concentric circles are in the ratio $1: 2: 3,$ then find the ratio of the areas of three regions.

Find the area of the flower bed (with semi-circular ends) shown in $Fig.$